Thermal transport in SiC nanostructures

TL;DR

This paper investigates how interface scattering and internal reflection in SiC nanostructures hinder phonon transport, significantly reducing thermal conductivity and heat flow, which impacts high-power device performance.

Contribution

It reveals the dominant role of interface scattering and internal reflection in limiting heat dissipation in SiC nanostructures, providing new insights into thermal transport mechanisms.

Findings

Interface scattering reduces thermal conductivity below traditional predictions.

Total-internal reflection limits heat flow across metal/SiC interfaces.

Optimal heat flow occurs with small sound velocity differences.

Abstract

SiC is a robust semiconductor material considered ideal for high-power application due to its material stability and large bulk thermal conductivity defined by the very fast phonons. In this paper, however, we show that both material-interface scattering and total-internal reflection significantly limit the SiC-nanostructure phonon transport and hence the heat dissipation in a typical device. For simplicity we focus on planar SiC nanostructures and calculate the thermal transport both parallel to the layers in a substrate/SiC/oxide heterostructure and across a SiC/metal gate or contact. We find that the phonon-interface scattering produces a heterostructure thermal conductivity significantly smaller than what is predicted in a traditional heat-transport calculation. We also document that the high-temperature heat flow across the metal/SiC interface is limited by total-internal reflection effects and maximizes with a small difference in the metal/SiC sound velocities.